remove superfluous #ifdef VERIFY/#endif preprocessor conditions

Now that the `VERIFY_CHECK` compiles to empty in non-VERIFY mode, blocks
that only consist of these macros don't need surrounding `#ifdef VERIFY`
conditions anymore.

At some places intentional blank lines are inserted for grouping and
better readadbility.

src/scalar_low_impl.h

@@ -61,11 +61,9 @@ static void secp256k1_scalar_cadd_bit(secp256k1_scalar *r, unsigned int bit, int
         *r += ((uint32_t)1 << bit);
 
     secp256k1_scalar_verify(r);
-#ifdef VERIFY
     VERIFY_CHECK(bit < 32);
     /* Verify that adding (1 << bit) will not overflow any in-range scalar *r by overflowing the underlying uint32_t. */
     VERIFY_CHECK(((uint32_t)1 << bit) - 1 <= UINT32_MAX - EXHAUSTIVE_TEST_ORDER);
-#endif
 }
 
 static void secp256k1_scalar_set_b32(secp256k1_scalar *r, const unsigned char *b32, int *overflow) {